[Feature]: Allow pipeline to drop output node

[jaelgu]

Is there an existing issue for this?

• [X] I have searched the existing issues.

Is your feature request related to a problem? Please describe.

Sometimes we need to combine pipelines, however all auto pipelines are RuntimePipeline, which is not allowed in concat. Can we allow a runtime pipeline to drop output node, which makes it a regular pipeline?

Describe the solution you'd like.

No response

Describe an alternate solution.

No response

Anything else? (Additional Context)

No response

[junjiejiangjjj]

https://towhee.readthedocs.io/en/latest/pipeline/usage.html#pipeline-act-as-node use it to combine pipelines

[Chiiizzzy]

Currently can be solved by pipeline-as-operator, will support disabling pre-load in the future to prevent duplicated loading of model in the future.